#include <stdio.h>
#include <math.h>
void CalculateRealRoot(double a1,double b1,double c1);
int main(void)
{
	double a,b,c;
	
	printf("please input a:");
	scanf("%lf",&a);
	printf("please input b:");
	scanf("%lf",&b);
	printf("please input c:");
	scanf("%lf",&c);
	CalculateRealRoot(a,b,c);
	return 0;
}
void CalculateRealRoot(double a1,double b1,double c1)
{
	double delta,x1,x2;
	delta=b1*b1-4*a1*c1;
	if(delta<0)
	{
		printf("No Real Root.\n"); 
	}
	else
	{
	        x1=(-b1+sqrt(delta))/(2*a1);
			x2=(-b1-sqrt(delta))/(2*a1);
		    printf("x1=%lf,x2=%lf.\n",x1,x2);
		
	}
}
